1. Field of the Invention
This invention relates to an exposure control device in a camera using an electro-optic light control element whose transmittivity to light is variable by electrical signal.
2. Description of the Prior Art
There is a well-known idea of constructing means for controlling light, for example, a shutter, by applying an electric field to an electro-optic substance such as Kerr cell, single crystal, liquid crystal, suspension containing dipole molecules having a light-abosrbing characteristic, dielectric ceramics or electrochromic substance. However, a shutter using such an electro-optic substance permits passage of light therethrough to some extent even during the so-called intercepting condition, namely, the condition in which light must not be passed, and thus, it has been inferior in light intercepting performance to common shutters formed of metal plates or the like and accordingly, has been poor in utility as the light control means which is to be incorporated in ordinary cameras.
It is also known to construct a disphragm by applying a voltage to some of electrodes formed into a plurality of divided annular belts to thereby apply an electric field and form a predetermined configuration of opening (see Japanese Patent Publication No. 806/1969). Nevertheless, no concrete technique for applying the voltage to such electrodes has so far been proposed.